<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>555</title>
    <script>
// // //1.将A5F3转成2进制
var a='A5F3';
 var a1=parseInt(a,16);
var a3=a1.toString(2);
alert(a3)

    </script>
</head>
<body>
    <script>
// 2.99乘法表
var sum=''
for(var b=1; b<=9;b++){
    for(var c=1; c<=b; c++){
     sum=sum+b+'*'+c+'='+b*c+' &nbsp;&nbsp'
    }
   sum+='<br>'  
}
document.write(sum)

// 3.输入年月，（用数组）
//       3.1.计算当月有多少天
//       3.2.计算还剩多少天
var time = prompt('请输入年月')
const arr = str.split('.')  
var year =arr [0];
var month =arr[1];
var day =arr[2];
var daysum=30;
if(month!=2){
    switch(month){
        case 1:
        case 3:
        case 5:
        case 7:
        case 8:
        case 10:
        case 12:
            daysum=31;
            break;
            default:break;
    }
    
}else{
    if(year%400==0){
        daysum=29
    }else if(year%4==0&&year%100!=0){
        daysum=29
    }else{
        daysum=28
    }
}
document.write(daysum)
    </script>
</body>
</html>